The specific aims of this protocol are: 1)to assess the toxicities of and determine the maximum tolerated dose (MTD) of subcutaneous calcitriol given Day 1 - 3 in combination with carboplatin (ABC = 6) Day 3. 2)to assess the toxicities of and determine the maximum tolerated dose (MTD) of carboplatin Day 3 when given with subcutaneous calcitriol Day 1 - 3 at a dose one dosage level less than the MTD. 3)to determine the effect of administration of calcitriol on the AUC of carboplatin. 4)to assess the relationship between the ABC of carboplatin and the myelosuppression seen following the administration of carboplatin + calcitriol. 5)to evaluate the safety and efficacy of carboplatin + calcitriol in patients with malignant glioma. Additionally, this will allow us to gather important information regarding drug interactions.